package com.lagou.sqlSession;

import com.lagou.config.BoundSql;
import com.lagou.pojo.Configuration;
import com.lagou.pojo.MappedStatement;
import com.lagou.utils.ParameterMapping;

import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class SimpleExecutor implements Executor {

    @Override
    public <E> List<E> query(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        // 1.注册驱动，获取链接
        Connection connection = configuration.getDataSource().getConnection();

        /**
         * 2.获取sql语句
         * 转换sql，并对自定义参数#{}内容进行解析存储
         */
        String sql = mappedStatement.getSql();
        BoundSql boundSql = new BoundSql(sql);

        //3.获取预处理对象 preparedStatement
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSql());

        //4。获取参数全路径并设置参数
        String paramterType = mappedStatement.getParamterType();
        Class<?> paramTypeClass =  getClassType(paramterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for (int i = 0; i < parameterMappingList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();

            //反射
            Field declaredField = paramTypeClass.getDeclaredField(content);
            //暴力访问，防止私有
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);

            preparedStatement.setObject(i+1,o);

        }


        //5.执行sql
        ResultSet resultSet = preparedStatement.executeQuery();



        //6.封装返回结果集
        ArrayList<Object> objects = new ArrayList<>();

        String resultType = mappedStatement.getResultType();
        Class<?> resultTypeClass = getClassType(resultType);

        while (resultSet.next()){

            Object o = resultTypeClass.newInstance();

            ResultSetMetaData metaData = resultSet.getMetaData();
            for (int i = 1; i <= metaData.getColumnCount(); i++) {

                //获取字段名
                String columnName = metaData.getColumnName(i);
                Object value = resultSet.getObject(columnName);

                //内省
                PropertyDescriptor propertyDescriptor = new PropertyDescriptor(columnName,resultTypeClass);
                Method writeMethod = propertyDescriptor.getWriteMethod();
                writeMethod.invoke(o,value);
            }
            objects.add(o);

        }


        return (List<E>) objects;
    }

    public Integer update(Configuration configuration, MappedStatement mappedStatement, Object[] params) throws SQLException, ClassNotFoundException, NoSuchFieldException, IllegalAccessException {
        // 1.注册驱动，获取链接
        Connection connection = configuration.getDataSource().getConnection();

        /**
         * 2.获取sql语句
         * 转换sql，并对自定义参数#{}内容进行解析存储
         */
        String sql = mappedStatement.getSql();
        BoundSql boundSql = new BoundSql(sql);

        //3.获取预处理对象 preparedStatement
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSql());

        //4。获取参数全路径并设置参数
        String paramterType = mappedStatement.getParamterType();
        Class<?> paramTypeClass =  getClassType(paramterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for (int i = 0; i < parameterMappingList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();

            //反射
            Field declaredField = paramTypeClass.getDeclaredField(content);
            //暴力访问，防止私有
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);

            preparedStatement.setObject(i+1,o);

        }


        //5.执行sql
        Integer result = preparedStatement.executeUpdate();



        //6.返回结果集
        return result;
    }

    private Class<?> getClassType(String paramterType) throws ClassNotFoundException {
        if(paramterType!=null){
            return Class.forName(paramterType);
        }else{
            return null;
        }
    }

}
